Grapple-like tools attachable to the dipper stick of a backhoe have been known previously and have been particularly useful for loading various types of materials into a truck or gathering materials and placing them in a pile on the ground for future handling. For actual raking along the ground so as to clean debris off a site, the previously known grapples have had limited usefulness, primarily because the lower jaw has the teeth curved in the wrong direction and furthermore, the lower jaw is effectively in the way of using the upper jaw for efficient raking over the surface of the ground. Two earlier patents illustrate prior grapples which are constructed so that raking of debris along the surface of the ground cannot be efficiently carried out. In U.S. Pat. No. 3,802,731, the lower jaw is mounted on the end of the dipper stick, but illustrates a rigid strut which prevents swinging of the lower jaw. In some instances, the rigid strut retaining the lower jaw is replaced with a hydraulic cylinder, but primarily for the purpose of closing the lower jaw toward the upper jaw, and as a result the lower jaw continues to be in the way for efficient raking through the use of a top jaw.
In U.S. Pat. No. 4,248,471, another grapple assembly is illustrated and in this form the lower jaw is swingable relative to the dipper stick and the strut, but the attachment to the inner end of the upper jaw is spaced from the pivot on the dipper stick so that as the upper jaw is swung downwardly into a suitable raking position, the lower jaw is clearly in the wrong position so that the upper jaw can be used as a rake.
None of the other prior art presents any more suitable solution to an efficient raking function than is illustrated by these two patents.